Recently, a vehicle-mounted system equipped with a plurality of image input devices is disseminating. For example, there is a system in which cameras are installed on the front, back, left, and right of an automobile, respectively, and all of the surrounding environments are shown to a user, who is a driver, by video images to enhance safety during driving.
In such a system, sometimes, the images viewed from a virtual viewpoint (for example, video images as if looking down from above the vehicle) are generated in order to display more easy-to-understand images to the user. In this process, each of the input images has to be subjected to conversion processing so as to form the images viewed from the virtual viewpoint.
Moreover, not only the images like those of the look-down conversion, but also the images which have undergone correction of lens distortion are also required in order to facilitate image processing. Also in this case, the images have to be subjected to conversions as preprocessing. In this manner, obtaining the transform images corresponding to uses is required as needs. The number of the usages is not always limited to one; for example, it is required to obtain the look-down images to be shown to the user and distortion-corrected images for carrying out image processing from one input image.
As a configuration that obtains the transform images, for example, a configuration in which an image-pickup device, correcting means, and a storage medium are mutually connected via a bus is conceivable as described in Japanese Patent Application Laid-Open Publication No. 2003-333588 (Patent Document 1).
In Japanese Patent Application Laid-Open Publication No. 2001-145012 (Patent Document 2) and Japanese Patent Application Laid-Open Publication No. 2007-114923 (Patent Document 3), a small-volume buffer is provided between an image-pickup device and correcting means to provide a measure for shortening the processing time that is taken from video-image input to image conversion.